An area in which new solutions are constantly being sought is the problem area of how to prevent heat buildup and blowouts in vulcanized rubber compositions. How to improve the dynamic wire cord adhesion of vulcanized rubber compositions is also important, especially in the area of belted tires.
It is well known to use carbon black as an ingredient in rubber compositions in order to impart favorable characteristics to the rubbers. A broad variety of carbon blacks has been disclosed in the art. Since carbon black cannot be sufficiently characterized by its chemical composition or by its ingredients, it has become widely accepted to characterize a carbon black by the properties it exhibits. For example, a carbon black can be characterized by its surface area (which is usually a measurement of the size of the nodules making up the carbon black). Another important characteristic of a carbon black is its structure, which is a measure of the complexity of the individual carbon black aggregates or of the number of nodules which are "fused" together in one carbon black aggregate. Another important characteristic (which is defined below) is the tint residual of a carbon black.
The properties of carbon blacks are measured by using standardized ASTM tests; and those tests define those properties.
Resistance of degradation of rubber specimens is indirectly measured by ASTM D 623-67, which directly measures the time to blowout of specimens under stress. Generally, when time to blowout of a specimen is relatively high, heat buildup (as measured by .DELTA.T) in the specimen will be relatively low. However, it is not necessarily true that of two different specimens, the one having the higher time to blowout will have the lower heat buildup since resistance to degradation may be different in the two specimens.
Recently, in the prior art, it has been found that by using a carbon black with a low tint residual in a vulcanizable rubber composition, one will obtain a rubber composition which after vulcanizing has a significantly lower heat buildup (or hysteresis) than one obtains by incorporating a carbon black with a higher tint residual in the same rubber composition, the abrasion resistance of such rubber compositions incorporating these two different carbon blacks being essentially equal.
By using a carbon black having a highly negative tint residual value in a particular rubber, one produces a significantly improved rubber composition over those disclosed in the prior art.
It is an object of this invention to produce a vulcanizable rubber composition having low heat buildup properties and long times to blowout after vulcanization.
It is a further object of this invention to produce a vulcanized rubber composition with low heat buildup properties and long times to blowout.
It is a still further object of this invention to produce articles of manufacture with low heat buildup properties and long times to blowout.
Yet another object of this invention is to produce a vulcanizable rubber composition with high dynamic wire cord adhesion after vulcanization.
A further object of this invention is to produce a vulcanized rubber composition with high dynamic wire cord adhesion.
A still further object of this invention is to produce articles of manufacture with high dynamic wire cord adhesion.